FIRING GEAR Under the conditions that prevail in a naval action, it is of great importance that the means of firing the gun should be as instantaneous and as reliable as possible. Where guns are directly fired from a control or director position, it is necessary for the main chain to the gun to be electrical, and the "firing interval" is reduced if this circuit fires an electric tube. Where a per cussion tube is employed to fire the gun, the fire control circuit is arranged to release a striker by energising an electromagnet and attracting an armature which releases the trigger. Owing to the mechanical movements involved, this latter method entails a longer delay.
The firing interval in the case of an electric tube is determined by the following train of events :—(i) Brain impulse interval between the director layer or gunlayer seeing his sight alined with the target and deciding to fire, and his finger pressing the con tact button. (2) Completion of the circuit by the physical move ment of the contact button, push or switch. (3) Heating the bridge and burning the powder in the tube. (4) The passage of the tube flash along the vent of the breech screw. (5) Ignition of the primer on the end of charge. (6) Ignition of charge. (7) Time taken by the projectile in passing down the bore.
An efficient firing gear reduces the firing interval to a minimum and makes the prospect of firing as reliable as possible. The possibility, however, of a misfire is usually provided for by some alternative system. In some cases an alternative electrical circuit is fitted which is brought into operation by a switch, and in other cases percussion firing is resorted to by either exchanging the electric tube for a percussion one or by employing a tube which is capable of being fired electrically and by percussion. Electrical
firing lends itself very readily to the introduction of safety arrangements, e.g., the circuit can be broken by the recoiling action of the gun and only completed when the gun is out in the firing position. It can be also broken when the breech is not closed and only completed when it is fully closed.
It will be evident from the foregoing that the use of a heavy naval gun entails great proficiency in drill and a consider able amount of organisation and intelligent co-operation in the personnel involved. The machinery and instruments concerned must be kept in a highly efficient condition to ensure that no link in the chain of operations fails. Alternative methods of load ing and operating turret guns are provided in many cases, such as mechanical hand-loading or a secondary source of power in the event of the main system being put out of action. These add to the degree of training and skill required in the gun's crew. However great the power and mechanical perfection of the weapons, the spirit, resource, and efficiency of the man behind the gun will continue to be a matter of the highest importance. Other things being equal—the human element will decide the issue. (J. G. M. McH.) ORDOS: see SHENSI.